Centipedes ( Myriapoda ) are small arthropods that can actually have a lot of legs, sometimes more than a thousand . Although they are rather unpleasant to look at, they are generally harmless, and many of them are beneficial by eating insect pests. However, most centipedes themselves do not at all seek to make contact with large animals, staying away from the light, in the darkest corners and forest floor.
Because of this lifestyle, their vision is greatly reduced. Many species of Myriapoda do not have eyes at all and rely solely on the sense of smell to hunt insects, spiders and worms. However, the question arises: how exactly do they avoid light if they cannot see it? Scientists from the Northeastern University of Forestry in Harbin, China, were able to answer, whose article was published in the journal PNAS .
Shilong Yang and colleagues studied the poisonous Scolopendra subspinipes . The powerful toxin of these centipedes allows them to successfully hunt prey much larger than themselves, including lizards and even mice. But all this is in the dark; in the light, centipedes themselves easily become the prey of other predators, birds and snakes. Therefore, they are especially careful to avoid lighting, despite the complete absence of eyes.
To find out how these centipedes see, scientists placed them in a pair of containers connected to each other under the light of a lamp. At the same time, one container remained transparent, while the other was tightly tightened with black tape. An infrared camera was used to monitor centipedes. It turned out that the antennae of animals most actively react to lighting, which, when moving from darkness to light, quickly heated up from 28 to 37 degrees Celsius.
Additional experiments have shown that sensory neurons located in the antennas, or rather, the BRTNaC1 receptors working in them, play a key role in this. In response to changes in temperature, they actively pump ions through the membranes of nerve cells, triggering a signal that causes the corresponding avoidance reaction. This was confirmed by covering the antennas with the thinnest foil: such centipedes remained in the light much longer than usual.
Scientists suggest that S. subspinipes are far from the only animals that have managed to “repurpose” their temperature receptors, using them to perceive light. Therefore, now the authors of the new work intend to conduct similar studies of other “eyeless” arthropods, including beetles and roaming ants.